If you use the XMLRPC client in ruby over a self certified SSL you have this warning :
warning: peer certificate won’t be verified in this SSL session
You can get override that warning cleanly (i have seen some people who just comment the message in the standard library) like that :

require ‘xmlrpc/client’
 
require ‘net/https’
require ‘openssl’
require [...]

While talking with my fellow colleague Darren Birkett about what seems a design limitation
of yum to not be able to force listing the excludes from yum. I had a
shoot to make a yum plugin to force listing the excludes.
Here is how it works :
root@centos5:~> grep exclude /etc/yum.conf
exclude=rpm*
root@centos5:~> yum install rpm-devel
Loading “installonlyn” plugin
Loading “changelog” plugin
Loading “chmouel” [...]